The runtime poller: one conditional fetch of GET /sdk/v1/gates/runtime at boot (via handle_continue, so the supervisor is never blocked), then again every refresh_interval.

Failure semantics: fetch errors are contained — they emit [:lucerna, :sync, :error] telemetry and the current snapshot keeps answering (fail-stale). A 401/403 additionally settles the Store's ready gate as auth-failed so wait_until_ready surfaces the bad key. Only genuine bugs crash this process, and the supervisor restarts it without touching the Store.